What is a "Tornado" ?

What you need to know about tornados:

1. Scientists don't know exactly how tornadoes form, but that they usually occur in the United States when cool dry air from the north mixes with warm moist air from the south.

Find out by yourselves:

- What is a twist? - What is a tornado alley?

2. Watch the following National Geographic Videos. What did you notice about tornadoes?

3. Tornados are found most frequently east of the Rocky Mountains during the spring and summer months. Find out how tornados form here.
4. In an average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500 injuries.
5. The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Damage paths can be in excess of one mile wide and 50 miles long. Once a tornado in Broken Bow, Oklahoma, carried a motel sign 30 miles and dropped it in Arkansas!